Paypal is a good one. (Just kidding.) Are you looking for a service that will take a sum of money and distribute it to worthy charities or suggestions of worthy recipients of your donations?
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WAFJun 6 '11 at 14:06

Basically, if you can think of a Jewish organization, pop their name into Google (or the like) and make sure the site you're on is actually legit [not such an easy task, but common sense will generally help].

Of course there are some who don't have a donation website (at least yet). For those you'll just have to leave your seat.

Colel Chabad is the oldest continuously operating Tzedakah organization in Israel. It was established in 1788 by Rabbi Schneur Zalman of Liadi, founder of the Chabad Lubavitch movement. Colel Chabad is a 501(c)3 tax exempt organization.

Colel Chabad's sole purpose has always been to help the most destitute residents of Israel in a manner that preserves and enhances their dignity. For over 200 years Colel Chabad has remained faithful to its mission to help any Jew regardless of age, gender, marital status, ethnic background, location, or degree of observance.

Also, Bank of America lets me send a check directly from their website. All I do is put in how much money I want to send and 4 days later the check arrives at it's destination. This way I can send Tzedakah to any organization I want without leaving my chair or writing and delivering a check. This works great when paying for pledges given when getting an Aliyah. I am sure most other banks' online services lets you do the same thing. I can also schedule a number of checks over a period of time, which is great if I want to cut up the donation into smaller chunks.

I think some additional words need to be said about Lemaan Achai - while most charities give money to those who need it, Lemaan Achai is based on the old proverb "teach a man to fish and feed him for life". Thus LA really invests the money, creating even greater "return on investment" for charity. Hence their label of "smart chessed".
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AviDJun 7 '11 at 0:23

CharityNavigator lists thousands of charities, and gives the breakdown on their expenses. You can browse through the high rated ones here to find an appropriate charity. Yad Eliezer has very little overhead costs.